Two new spirotetronate natural products, lobophorin L (1) and lobophorin M(2), together with three known lobophorin-like spirotetronate antibiotics (3−5) and two known ansamycins (6−7), were isolated from the marine-derived Streptomyces sp. 4506. The structures of 1 and 2 were established on the basis
A bioassay‐guided fractionation led to the isolation of hangtaimycin (HTM) from Streptomyces spectabilis CCTCC M2017417 and the discovery of its hepatoprotective properties. Structure elucidation by NMR suggested the need for a structural revision. A putative HTM degradation product was also isolated and its structure was confirmed by total synthesis. The biosynthetic gene cluster was identified and resembles a hybrid trans‐AT PKS/NRPS biosynthetic machinery whose first PKS enzyme contains an internal dehydrating bimodule, which is usually found split in other trans‐AT PKSs. The mechanisms of such dehydrating bimodules have often been proposed, but have never been deeply investigated. Here we present in vivo mutations and in vitro enzymatic experiments that give first and detailed mechanistic insights into catalysis by dehydrating bimodules.
Eine durch Bioassay geleitete Fraktionierung führte zur Isolierung von Hangtaimycin (HTM) aus Streptomyces spectabilis CCTCC M2017417 und zur Entdeckung seiner hepatoprotektiven Eigenschaften. Die Strukturaufklärung per NMR zeigte die Notwendigkeit einer Strukturrevision. Ein putatives Abbauprodukt von HTM wurde ebenfalls isoliert und dessen Struktur wurde durch Totalsynthese bestätigt. Der Biosynthesegencluster wurde identifiziert und entspricht einer hybriden trans‐AT‐PKS/NRPS Biosynthesemaschinerie, dessen erstes PKS‐Enzym ein internes dehydatisierendes Bimodul enthält, welche in anderen trans‐AT PKSs üblicherweise gespalten vorliegen. Die Mechanismen solcher dehydatisierender Bimodule wurden oft vorgeschlagen, aber niemals genau untersucht. Hier präsentieren wir in vivo‐Mutationen und enzymatische in vitro‐Experimente, die erste und detaillierte Einblicke in die Katalyse durch dehydatisierende Bimodule geben.
ThermoSysPro (TSP) is a library for the modeling and simulation of power plants and energy systems. It has been developed by EDF and it is released under open source license. When developing models with TSP it is necessary to ensure that they match reality. In practice, this operation is performed by adjusting the value of the parameters appearing in the model. This major step corresponds to model calibration. Calibration can be performed through various methods. A classical way to do so with Modelica models is by model inversion. The major inconvenience of this method, in addition of potential convergence problems for complex models, is that it is necessary to have exactly the same number of measurements as parameters to be calibrated, which is not often the case in practice. This paper shows how data assimilation techniques can robustly be used for calibration of complex TSP models avoiding the inconveniences associated to calibration by model inversion while ensuring an optimal use of the available measurements. A complex TSP model of the secondary loop of a Pressurized Water Reactor (PWR) is considered for this purpose.
Germination is an effective method for improving the nutritional value of Tartary buckwheat (TB). The effects of exogenous additive treatments (caffeic acid (CA), L-phenylalanine (L-Phe), NaCl) on germination, main active component contents and antioxidant activities before and after in vitro digestion of germinated TB were investigated. Compared with the natural growth group, the T4 group (CA 17 mg/L, L-Phe 2.7 mmol/L, NaCl 2.7 mmol/L) treatment increased the germination rate (67.50%), sprout length, reducing sugar (53.05%), total flavonoid (18.36%) and total phenolic (20.96%) content, and antioxidant capacity of TB. In addition, exogenous additives treatment induced the consumption of a lot of nutrients during seed germination, resulting in a decrease in the content of soluble protein and soluble sugar. The stress degree of natural germination on seeds was higher than that of low concentrations of exogenous additives, resulting in an increase in malondialdehyde content. In vitro digestion leads to a decrease in phenolics content and antioxidant capacity, which can be alleviated by exogenous treatment. The results showed that treatment with exogenous additives was a good method to increase the nutritional value of germinated TB, which provided a theoretical basis for screening suitable growth conditions for flavonoid enrichment.
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